Both aerosol packages and pump packages of fluid products, commonly have a tubular dispensing stem through which the packaged product is expelled when the stem is moved, usually by depression of the stem. In the case of an aerosol package with the product pressurized, the stem movement opens an aerosol valve, and in the case of the pump-type package, depression of the stem works a mechanical pump which pressurizes and expells the product.
Because the tubular stem is normally moved by finger pressure, it is common to provide an actuator fixed to the top of the stem, both for providing for comfortable finger-pressure actuation of the stem and to provide an orifice or nozzle through which the product expelled into the actuator by movement of the stem, can discharge into the atmosphere with a spray pattern having the characteristics desired for the particular product discharged.
With product formulations which contain a liquified gas propellant, the explosive vaporization of the propellant and product when leaving the actuator orifice, is relied on to obtain the spray pattern desired, this permitting a very simple actuator design to be used. In the case of other product formulations such as those not containing a liquified gas propellant, mechanical breakup actuators have been used, which incorporate a swirl chamber in which the product is swirled as it is forced through the actuator so that the combined motions of swirling and axial flow through the actuator orifice, provide a mechanical breakup of the product and the consequent production of a spray having a pattern determined by the design of the actuator.
Some products have a tendency to clog the actuator and its orifice, and various so-called tip-sealing actuators have been proposed wherein the actuator orifice or nozzle is sealed automatically after each use, so that any product remaining within the actuator is sealed off from the outside atmosphere, it being air and/or evaporation into the air that causes clogging problems.
Examples of actuators emobdying the features of both a swirl chamber and tip sealing are provided by the present inventor's own U.S. Pat. Nos. 3,913,803 and 3,913,804, both issued Oct. 21, 1975. The constructions of both of these patents provide for automatic tip sealing, the provision of a swirl chamber, and the possibility of complete shut-off as is desirable for shipment of packages of the dispensing type.
Manufacturing costs of such actuators, whether for aerosol or pump-type packages, is an extremely important consideration, keeping in mind that such packages are produced in quantities running into many millions. To keep this cost down, it is desirable that if an actuator is to provide both a swirl chamber, always desirable and sometimes necessary, in conjunction with a positive shut-off, it is of prime importance that the construction involve as few parts as possible, that the parts can be made by high-production methods, particularly by injection-molding, since plastic parts are usually preferred, and that assembly of the parts involved be free from complications.
Anyone unfamiliar with the aerosol industry and the actuators referred to hereinabove, can refer to the text AEROSOLS: SCIENCE AND TECHNOLOGY, published by Interscience Publishers, Inc., New York, copyright 1961, with the understanding that aerosol packaging, due to possibly undeserved adverse publicity, is to some extent giving way to pump-type packages, which insofar as actuators are concerned, involve similar problems. The main difference is that in an aerosol package the aerosol valve has a tubular stem through which the packaged product is expelled when the stem is depressed, whereas in the pump-type package depression of a generally corresponding tubular stem, operates a mechanical pump which expells the packaged product through the stem. In both cases the product is expelled under pressure through the stem.